This invention relates to a protector for the sprocket of a bicycle, particularly a bicycle used for competitive rough terrain racing or for acrobatic free style manuevers.
Acrobatic bicycle maneuvering often involves a deliberate movement of the bicycle into an airborne condition. Similarly, during competitive racing over hilly terrain the bicycle can become airborne. When the bicycle returns to the ground it may strike the ground surface at an oblique angle. If the striking angle is severe enough, or if there is a stationary upstanding structure in the path of the bicycle the drive sprocket for the bicycle chain may impact against the stationary structure. A bicycle sprocket is designed to transmit rotary drive forces to the chain, but it is not designed to withstand blows caused by physical impact against stationary structures, e.g. when the bicycle is returning to the ground after an airborne manuever.
It has been proposed to equip bicyles with a protector for the drive sprocket so that airborne maneuvers can be carried out without damaging the sprocket. These sprocket protectors have been designed to fit particular bicycle models, such that any one sprocket protector is confined to use on only a few bicycle models.
The present invention is concerned with a sprocket protector that can fit onto a relatively large number of different bicycle models, thereby reducing inventory requirements and somewhat reducing the average manufacturing cost (due to the ability to use volume production techniques). The protector of the invention has some additional advantageous features, e.g. relatively high strength and low weight, and a reversible and replaceable skid plate construction.
In one form of the invention the protector comprises an arcuate curved protector body equipped with two upstanding struts. The forward one of these struts has a swivel connection to a clamp that is adapted to fit onto the bicycle frame just forwardly from the drive sprocket hub portion of the frame. This swivel connection enables the clamp to fit onto an upwardly angled tubular element of the frame, even though the angulation of the frame element may not be exactly the same from one bicycle to the next. The swivel connection between the clamp and the forwardmost strut constitutes a principal feature of this invention.
The protector body is preferably formed by two laterally-spaced curved tubes. The aforementioned struts have lower ends thereof extending into the space between the curved tubes; the struts are welded to the curved tubes to form a protector body that is relatively strong while at the same time being relatively light.
The lower faces of the curved tubes form a mounting surface for a curved face plate (skid plate) that is essentially coextensive with the tubes. The curved face plate is releasbly connected to the protector body so that it can be replaced after it has become worn, due e.g. to skidding or possible deformation after repeated contact with the ground or other stationary structures. The protector body and face plate are symmetrically formed (configured) so that the face plate can be turned (reversed) end-for-end on the protector body, e.g. in the event that only the front end of the face plate is worn.